Electro-optic devices such as liquid crystal cells are used in optical signal processing to control the passage of light beams through the processor. Optical signal processing is used in laser communication systems, optical recording and reading systems, and optical computing and associated interconnection architectures. One element commonly used in optical processing systems is a lens for focusing light beams on a particular point or in a desired pattern.
Liquid crystal (LC) cells used in optical processors typically control the passage of a light beam used in the signal processing. Although electro-optic devices such as LC cells typically have many desirable characteristics, such as rapid response, to date electro-optic liquid crystal lenses have proved to be rather cumbersome, requiring a large number of LC pixels (e.g., 100 or more independently controlled pixels in a device having a pixel pitch of about 100 .mu.m) with an associated grid of control electronics. Each independently controlled pixel requires an associated driver to generate signals to control the pixel in coordination with other pixels to provide the desired lens focusing effect. In addition to the complexity of the control electronics, such devices often exhibit substantial attenuation of the light passing through the lens as a result of the non-ideal focusing resulting from the non-quadratic index variation caused by the electric fields in the EO device resulting from the respective discrete voltages applied to respective electrodes.
It is an object of this invention to provide a high quality electro-optic lens (e.g., with a diffraction limited spot) that is compact, robust, readily fabricated, does not require extensive control electronics, and that efficiently focuses the light passing therethrough.